Substantial photo-response of InGaN p-i-n homojunction solar cells

InGaN p-i-n homojunction structures were grown by metal-organic chemical vapor deposition, and solar cells with different p-contact schemes were fabricated. X-ray diffraction measurements demonstrated that the epitaxial layers have a high crystalline quality. Solar cells with semitransparent p-contact exhibited a fill factor (FF) of 69.4%, an open-circuit voltage (V-oc) of 2.24 V and an external quantum efficiency (EQE) of 41.0%. On the other hand, devices with grid p-contact showed the corresponding values of 57.6%, 2.36 V, 47.9% and a higher power density. These results indicate that significant photo-responses can be achieved in InGaN p-i-n solar cells.

Silver(I) ions-enhanced electrochemiluminescence of tris(2,2-bipyridyl)ruthenium(II)

In this paper. we demonstrate an clectrochemiluminescence (ECL) enhancement of tris(2,2-bipyridyl)rutheniuin(II) (Ru(bpy)(3)(2+)) by the addition of silver(l) ions. The maximum enhancement factor of about 5 was obtained on a glassy carbon electrode in the absence of co-reactant. The enhancement of ECL intensity was possibly attributed to the unique catalytic activity of Ag+ for reactions between Ru(bpy)(3)(3+) with OR The higher enhancement was observed in phosphate buffer solutions compared with that from borate buffer solutions. This resulted from the fact that formation of nanoparticles with large surface area in the phosphate buffer solution exhibited high catalytic activity. The amount of Ag+, solution pH and working electrode materials played important roles for the ECL enhancement. We also studied the effects of Ag+ on Ru(bpy)(3)(2+)/tripropylamine and Ru(bpy)(3)(2+)/C2O42- ECL systems.

Identification and molecular analysis of a stress-inducible Hsp70 from Sciaenops ocellatus

Hsp70 proteins are a family of molecular chaperones that are involved in many aspects of protein homeostasis. In this study, an Hsp70 homologue (SoHsp70) was identified from red drum Sciaenops ocellatus and analyzed at molecular level. The open reading frame of SoHsp70 is 1920 bp and intronless, with a 5'-untranslated region (UTR) of 399 bp and a 3'-UTR of 241 bp. The deduced amino acid sequence of SoHsp70 shares 84-92% overall identities with the Hsp70s of a number of fish species. In silico analysis identified in SoHsp70 three conserved Hsp70 domains involved in nucleotide and substrate binding. The coding sequence of SoHsp70 was subcloned into Escherichia coli, from which recombinant SoHsp70 was purified and, upon ATPase assay, found to exhibit apparent ATPase activity. Expressional analysis showed that constitutive expression of SoHsp70 was detectable in heart, liver, spleen, kidney, brain, blood, and gill. Experimental challenges with poly(I:C) and bacterial pathogens of Gram-positive and Gram-negative nature induced SoHsp70 expression in kidney to different levels. Stress-responsive analysis of SoHsp70 expression in primary cultures of red drum hepatocytes showed that acute heat shock treatment elicited a rapid induction of SoHsp70 expression which appeared after 10 min and 30 min of treatment. Exposure of hepatocytes separately to iron, copper, mercury, and hydrogen peroxide significantly unregulated SoHsp70 expression in time-dependent manners. Vaccination of red drum with a Streptococcus iniae bacterin was also found to induce SoHsp70 expression. Furthermore, recombinant SoHsp70 enhanced the immunoprotective effect of a subunit vaccine. Taken together, these results suggest that SoHsp70 is a stress-inducible protein that is likely to play a role in immunity and in coping with environmental and biological stresses. (C) 2010 Elsevier Ltd. All rights reserved.

A role for LH in the regulation of expression of mRNAs encoding components of the insulin-like growth factor (IGF) system in the ovine corpus luteum

P.M. Hastie and W. Haresign (2006). A role for LH in the regulation of expression of mRNAs encoding components of the insulin-like growth factor (IGF) system in the ovine corpus luteum. Animal Reproduction Science, 96(1-2), 196-209. Sponsorship: DEFRA RAE2008

Współpraca transgraniczna i regionalna w obszarze Morza Bałtyckiego w latach 1989 -2007

Wydział Nauk Politycznych i Dziennikarstwa

Jak sprawić, aby nasze badania były widoczne i cytowane?

Prezentacja do wykładu wygłoszonego w Bibliotece Uniwersyteckiej w Toruniu 9 stycznia 2014 r.

Współpraca i rywalizacja państw jako czynnik kształtujący bezpieczeństwo międzynarodowe w Azji Północno-Wschodniej na początku XXI wieku

Wydział Nauk Politycznych i Dziennikarstwa

Human uterine leiomyoma-derived fibroblasts stimulate uterine leiomyoma cell proliferation and collagen type I production, and activate RTKs and TGF beta receptor signaling in coculture.

BACKGROUND: Uterine leiomyomas (fibroids) are benign smooth muscle tumors that often contain an excessive extracellular matrix (ECM). In the present study, we investigated the interactions between human uterine leiomyoma (UtLM) cells and uterine leiomyoma-derived fibroblasts (FB), and their importance in cell growth and ECM protein production using a coculture system. RESULTS: We found enhanced cell proliferation, and elevated levels of ECM collagen type I and insulin-like growth factor-binding protein-3 after coculturing. There was also increased secretion of vascular endothelial growth factor, epidermal growth factor, fibroblast growth factor-2, and platelet derived growth factor A and B in the media of UtLM cells cocultured with FB. Protein arrays revealed increased phosphorylated receptor tyrosine kinases (RTKs) of the above growth factor ligands, and immunoblots showed elevated levels of the RTK downstream effector, phospho-mitogen activated protein kinase 44/42 in cocultured UtLM cells. There was also increased secretion of transforming growth factor-beta 1 and 3, and immunoprecipitated transforming growth factor-beta receptor I from cocultured UtLM cells showed elevated phosphoserine expression. The downstream effectors phospho-small mothers against decapentaplegic -2 and -3 protein (SMAD) levels were also increased in cocultured UtLM cells. However, none of the above effects were seen in normal myometrial cells cocultured with FB. The soluble factors released by tumor-derived fibroblasts and/or UtLM cells, and activation of the growth factor receptors and their pathways stimulated the proliferation of UtLM cells and enhanced the production of ECM proteins. CONCLUSIONS: These data support the importance of interactions between fibroid tumor cells and ECM fibroblasts in vivo, and the role of growth factors, and ECM proteins in the pathogenesis of uterine fibroids.

Prolactin receptor signaling is essential for perinatal brown adipocyte function: a role for insulin-like growth factor-2.

BACKGROUND: The lactogenic hormones prolactin (PRL) and placental lactogens (PL) play central roles in reproduction and mammary development. Their actions are mediated via binding to PRL receptor (PRLR), highly expressed in brown adipose tissue (BAT), yet their impact on adipocyte function and metabolism remains unclear. METHODOLOGY/PRINCIPAL FINDINGS: PRLR knockout (KO) newborn mice were phenotypically characterized in terms of thermoregulation and their BAT differentiation assayed for gene expression studies. Derived brown preadipocyte cell lines were established to evaluate the molecular mechanisms involved in PRL signaling on BAT function. Here, we report that newborn mice lacking PRLR have hypotrophic BAT depots that express low levels of adipocyte nuclear receptor PPARgamma2, its coactivator PGC-1alpha, uncoupling protein 1 (UCP1) and the beta3 adrenoceptor, reducing mouse viability during cold challenge. Immortalized PRLR KO preadipocytes fail to undergo differentiation into mature adipocytes, a defect reversed by reintroduction of PRLR. That the effects of the lactogens in BAT are at least partly mediated by Insulin-like Growth Factor-2 (IGF-2) is supported by: i) a striking reduction in BAT IGF-2 expression in PRLR KO mice and in PRLR-deficient preadipocytes; ii) induction of cellular IGF-2 expression by PRL through JAK2/STAT5 pathway activation; and iii) reversal of defective differentiation in PRLR KO cells by exogenous IGF-2. CONCLUSIONS: Our findings demonstrate that the lactogens act in concert with IGF-2 to control brown adipocyte differentiation and growth. Given the prominent role of brown adipose tissue during the perinatal period, our results identified prolactin receptor signaling as a major player and a potential therapeutic target in protecting newborn mammals against hypothermia.

Explicit DNase sequence bias modeling enables high-resolution transcription factor footprint detection.

DNaseI footprinting is an established assay for identifying transcription factor (TF)-DNA interactions with single base pair resolution. High-throughput DNase-seq assays have recently been used to detect in vivo DNase footprints across the genome. Multiple computational approaches have been developed to identify DNase-seq footprints as predictors of TF binding. However, recent studies have pointed to a substantial cleavage bias of DNase and its negative impact on predictive performance of footprinting. To assess the potential for using DNase-seq to identify individual binding sites, we performed DNase-seq on deproteinized genomic DNA and determined sequence cleavage bias. This allowed us to build bias corrected and TF-specific footprint models. The predictive performance of these models demonstrated that predicted footprints corresponded to high-confidence TF-DNA interactions. DNase-seq footprints were absent under a fraction of ChIP-seq peaks, which we show to be indicative of weaker binding, indirect TF-DNA interactions or possible ChIP artifacts. The modeling approach was also able to detect variation in the consensus motifs that TFs bind to. Finally, cell type specific footprints were detected within DNase hypersensitive sites that are present in multiple cell types, further supporting that footprints can identify changes in TF binding that are not detectable using other strategies.

Involvement of Rel/Nuclear Factor-κB Transcription Factors in Keratinocyte Senescence

After a finite doubling number, normal cells become senescent, i.e. nonproliferating and apoptosis resistant. Because Rel/nuclear factor (NF)-κB transcription factors regulate both proliferation and apoptosis, we have investigated their involvement in senescence. cRel overexpression in young normal keratinocytes results in premature senescence, as defined by proliferation blockage, apoptosis resistance, enlargement, and appearance of senescence-associated β-galactosidase (SA-β-Gal) activity. Normal senescent keratinocytes display a greater endogenous Rel/NF-κB DNA binding activity than young cells; inhibiting this activity in presenescent cells decreases the number of cells expressing the SA-β-Gal marker. Normal senescent keratinocytes and cRel-induced premature senescent keratinocytes overexpressed manganese superoxide dismutase (MnSOD), a redox enzyme encoded by a Rel/NF-κB target gene. MnSOD transforms the toxic O2.- into H2O2, whereas catalase and glutathione peroxidase convert H2O2 into H2O. Neither catalase nor glutathione peroxidase is up-regulated during cRel-induced premature senescence or during normal senescence, suggesting that H 2O2 accumulates. Quenching H2O2 by catalase delays the occurrence of both normal and premature cRel-induced senescence. Conversely, adding a nontoxic dose of H2O2 to the culture medium of young normal keratinocytes induces a premature senescence-like state. All these results indicate that Rel/NF-κB factors could take part in the occurrence of senescence by generating an oxidative stress via the induction of MnSOD.

The NRF-1/α-PAL transcription factor regulates human E2F6 promoter activity

E2F6 is widely expressed in human tissues and cell lines. Recent studies have demonstrated its involvement in developmental patterning and in the regulation of various genes implicated in chromatin remodelling. Despite a growing number of studies, nothing is really known concerning the E2F6 expression regulation. To understand how cells control E2F6 expression, we analysed the activity of the previously cloned promoter region of the human E2F6 gene. DNase I footprinting, gel electrophoretic-mobility shift, transient transfection and site-directed mutagenesis experiments allowed the identification of two functional NRF-1/α-PAL (nuclear respiratory factor-1/α-palindrome-binding protein)-binding sites within the human E2F6 core promoter region, which are conserved in the mouse and rat E2F6 promoter region. Moreover, ChIP (chromatin immunoprecipitation) analysis demonstrated that overexpressed NRF-1/α-PAL is associated in vivo with the E2F6 promoter. Furthermore, overexpression of full-length NRF-1/α-PAL enhanced E2F6 promoter activity, whereas expression of its dominant-negative form reduced the promoter activity. Our results indicate that NRF-1/α-PAL is implicated in the regulation of basal E2F6 gene expression.

The evolutionarily conserved transcription factor PRDM12 controls sensory neuron development and pain perception

PR homology domain-containing member 12 (PRDM12) is a highly evolutionary conserved member of the Prdm family of transcription factors that play essential roles in many cell fate decisions. In human, PRDM12 coding mutations have been recently identified in several patients with hereditary sensory and autonomic neuropathy (HSAN) (submitted elsewhere). Here we show that PRDM12 is involved in sensory neurogenesis in Xenopus and that several of the human Prdm12 mutants show altered structure, subcellular localization and function. In Drosophila, we demonstrate that the sensory neuron specific RNAi knockdown of the Prdm12 ortholog Hamlet induces impaired nociception and that a similar phenotype is observed in hypomorph hamlet mutants. In human fibroblasts of patients with PRDM12 mutations, we identified additional possible downstream target genes including thyrotropin-releasing hormone degrading enzyme (TRHDE). Knock-down of fly TRHDE in sensory neurons resulted in altered nociceptive neurons and impaired nociception. Collectively, these findings provide the first evidence showing that Prdm12 plays an important role in sensory neuron development. They also suggest that it has a critical evolutionarily conserved role in pain perception via modulation of the TRH signaling pathway.

Estudio ecológico comparado de los jarales de Madrid, I. Variación anual de la humedad del suelo

Durantedos años consecutivos se ha estudiado el contenido en agua de las capas superficiales del suelo de 29 parcelas pobladas por distintas unidades de jaral pertenecientes a la alianza Cistion laurifolii. Se aportan gráficas sobre la marcha de los contendio hídricos disponibles de los suelos, poniéndose de relieve la existencia de dos periodos: uno húmedo, caracterizado por existir agua disponible más o menos abundante, y otro seco en el que no existe agua disponible en los niveles superficiales del suelo. La duración de estos periodos se discute relacionándola con el régimen de precipitaciones, valorándose la importancia de éste frente a las precipitaciones totales anuales. Se comparan los distintos sintáxones para el factor hídrico por medio de análisis multivariables, determinándose la diferenciación de éstos en base a dicho factor.

Alcohol: a recently identified risk factor for breast cancer

Acknowledgements: I thank Dr. Barbour Warren, arriet Richardson and Alison James for their helpful input.